code: def try_lockf_on_other_process(fname, cmd):
      f = open(fname, "wb+")
      fcntl.lockf(f, cmd)
      fcntl.lockf(f, fcntl.LOCK_UN)
      f.close()
  
imports: import multiprocessing
  import platform
  import os
  import struct
  import sys
  import unittest
  from test.support import verbose, cpython_only, get_pagesize
  from test.support.import_helper import import_module
  from test.support.os_helper import TESTFN, unlink
label_desc: Use image node_id 2 for calling a global function with example usage: try_lockf_on_other_process(fname, cmd) without return types